CS5373A
Low-power, High-performance
∆Σ
Modulator and Test DAC
Modulator Features
Fourth-order
∆Σ
Architecture
•
•
•
•
Clock-jitter-tolerant architecture
Input signal bandwidth: DC to 2 kHz
Max AC amplitude: 5 V
pp
differential
Max DC amplitude: ± 2.5 V
dc
differential
Description
The CS5373A is a high-performance, fourth-order
∆Σ
modulator integrated with a
∆Σ
digital-to-analog convert-
er (DAC). When combined with a CS3301A / CS3302A
differential amplifier and the CS5378 digital filter, a
small, low-power, self-testing, high-accuracy, single-
channel measurement system results.
The modulator has high dynamic range and low total har-
monic distortion with very low power consumption. It
converts differential analog input signals from the
CS3301A / CS3302A amplifier to an oversampled serial
bit stream at 512 kbits per second. This oversampled bit
stream is then decimated by the CS5378 digital filter to a
24-bit output at the selected output word rate.
The test DAC operates in either AC or DC test modes.
AC test modes measure system dynamic performance
through THD and CMRR tests while DC test modes are
for gain calibration and pulse tests. It has two sets of dif-
ferential analog outputs,
OUT
and
BUF,
as dedicated
outputs for testing the electronics channel and for in-
circuit sensor tests. Output attenuation settings are
binary weighted and match the gain settings of the
CS3301A / CS3302A differential amplifiers for full-scale
testing at all gain ranges.
ORDERING INFORMATION
See
page 39.
VA+
VREF+
VREF-
VD
High Dynamic Range
• 127 dB SNR @ 215 Hz BW (2 ms sampling)
• 124 dB SNR @ 430 Hz BW (1 ms sampling)
Low Total Harmonic Distortion
• -118 dB THD typical (0.000126%)
• -112 dB THD maximum (0.000251%)
Low Power Consumption:
25 mW, 10 µW
Test DAC Features
Digital
∆Σ
Input from CS5378 Digital Filter
Selectable Differential Analog Outputs
• Precision output (OUT±) for electronics tests
• Buffered output (BUF±) for sensor tests
Multiple AC and DC Operational Modes
• Output signal bandwidth: DC to 100 Hz
• Max AC amplitude: 5 V
pp
differential
• Max DC amplitude: + 2.5 V
dc
differential
Selectable Attenuation for CS3301A / CS3302A
• 1, 1/2, 1/4, 1/8, 1/16, 1/32, 1/64
Outstanding Performance
• AC (OUT): -116 dB THD typical, -112 dB max
• AC (BUF): -108 dB THD typical, -90 dB max
• DC absolute accuracy: 0.4% typical, 1% max
INR+
INF+
INF-
INR-
OUT+
MDATA
24-Bit
∆Σ
Modulator
MFLAG
Clock
Generator
MCLK
MSYNC
Low Power Consumption
• AC modes / DC modes: 40 mW / 20 mW
• Sleep mode / Power down: 1 mW / 10 µW
Common Features
Extremely Small Footprint
• 28-pin SSOP package, 8 mm x 10 mm
TDATA
OUT-
BUF+
BUF-
Attenuator
1/1 to 1/64
24-Bit
∆Σ
Test DAC
CAP+
CAP-
Bipolar Power Supply Configuration
• VA+ = +2.5 V; VA- = -2.5 V; VD = +3.3 V
VA-
ATT(0, 1, 2)
MODE(0, 1, 2)
GND
http://www.cirrus.com
Copyright
©
Cirrus Logic, Inc. 2006
(All Rights Reserved)
DEC ‘06
DS703F1
CS5373A
TABLE OF CONTENTS
1. CHARACTERISTICS AND SPECIFICATIONS ........................................................................ 4
SPECIFIED OPERATING CONDITIONS ................................................................................. 4
TEMPERATURE CONDITIONS ............................................................................................... 5
ABSOLUTE MAXIMUM RATINGS ........................................................................................... 5
ANALOG INPUT CHARACTERISTICS ................................................................................... 6
ANALOG OUTPUT CHARACTERISTICS ............................................................................... 7
MODULATOR CHARACTERISTICS ........................................................................................ 8
PERFORMANCE PLOTS ......................................................................................................... 9
DAC AC DIFFERENTIAL MODES 1, 2, 3............................................................................... 10
DIGITAL CHARACTERISTICS .............................................................................................. 15
POWER SUPPLY CHARACTERISTICS ................................................................................ 18
2. GENERAL DESCRIPTION ..................................................................................................... 19
2.1 Delta-Sigma Modulator .................................................................................................... 19
2.2 Digital-to-Analog Converter .............................................................................................. 19
3. SYSTEM DIAGRAM ............................................................................................................ 20
4. POWER MODES ..................................................................................................................... 21
4.1 Power Down ..................................................................................................................... 21
4.2 Sleep Mode ...................................................................................................................... 21
4.3 Modulator Mode ............................................................................................................... 21
4.4 AC Test Modes ................................................................................................................ 21
4.5 DC Test Modes ................................................................................................................ 21
5. OPERATIONAL MODES ........................................................................................................ 22
5.1 Modulator Mode ............................................................................................................... 22
5.1.1 Modulator One’s Density ..................................................................................... 22
5.1.2 Modulator Decimated Output .............................................................................. 22
5.1.3 Modulator Synchronization .................................................................................. 22
5.1.4 Modulator Idle Tones .......................................................................................... 23
5.1.5 Modulator Stability ............................................................................................... 23
5.2 AC Test Modes ................................................................................................................ 23
5.2.1 AC Differential ..................................................................................................... 23
5.2.2 AC Common Mode .............................................................................................. 24
5.2.3 DAC Stability ....................................................................................................... 24
5.3 DC Test Modes ................................................................................................................ 24
5.3.1 DC Common Mode ............................................................................................. 24
5.3.2 DC Differential ..................................................................................................... 25
5.4 Sleep Mode ...................................................................................................................... 25
6. DIGITAL SIGNALS ................................................................................................................. 26
6.1 MCLK Connection ............................................................................................................ 26
6.2 MSYNC Connection ......................................................................................................... 26
6.3 MDATA Connection ......................................................................................................... 27
6.4 MFLAG Connection ......................................................................................................... 27
6.5 TDATA Connection .......................................................................................................... 27
6.6 GPIO Connections ........................................................................................................... 27
7. ANALOG SIGNALS ................................................................................................................ 28
7.1 INR±, INF± Modulator Inputs ........................................................................................... 28
7.1.1 Modulator Input Impedance ................................................................................ 28
7.1.2 Modulator Anti-alias Filter ................................................................................... 28
7.2 DAC Output Attenuation .................................................................................................. 29
7.3 DAC OUT± Precision Output ........................................................................................... 29
7.4 DAC BUF± Buffered Output ............................................................................................. 30
7.5 DAC CAP± Connection .................................................................................................... 30
7.6 Analog Differential Signals ............................................................................................... 30
8. VOLTAGE REFERENCE ........................................................................................................ 31
2
DS703F1
CS5373A
8.1 VREF Power Supply ........................................................................................................ 31
8.2 VREF RC Filter ................................................................................................................ 31
8.3 VREF PCB Routing ......................................................................................................... 31
8.4 VREF Input Impedance ................................................................................................... 31
8.5 VREF Accuracy ............................................................................................................... 32
8.6 VREF Independence ....................................................................................................... 32
9. POWER SUPPLIES ................................................................................................................ 33
9.1 Power Supply Bypassing ................................................................................................. 33
9.2 PCB Layers and Routing ................................................................................................. 33
9.3 Power Supply Rejection .................................................................................................. 33
9.4 SCR Latch-up .................................................................................................................. 34
9.5 DC-DC Converters .......................................................................................................... 34
10. TERMINOLOGY ................................................................................................................... 35
11. PIN DESCRIPTION ............................................................................................................... 36
12. PACKAGE DIMENSIONS .................................................................................................... 38
13. ORDERING INFORMATION ............................................................................................... 39
14. ENVIRONMENTAL, MANUFACTURING, & HANDLING INFORMATION .......................... 39
15. REVISION HISTORY ........................................................................................................... 40
LIST OF FIGURES
Figure 1. Modulator Noise Performance ......................................................................................... 9
Figure 2. Modulator + Test DAC Dynamic Performance................................................................. 9
Figure 3. Digital Input Rise and Fall Times ................................................................................... 15
Figure 4. System Timing Diagram................................................................................................. 17
Figure 5. MCLK / MSYNC Timing Detail ....................................................................................... 17
Figure 6. CS5373A Block Diagram ............................................................................................... 19
Figure 8. Connection Diagram ...................................................................................................... 20
Figure 7. System Diagram ............................................................................................................ 20
Figure 9. Power Mode Diagram .................................................................................................... 21
Figure 10. AC Differential Modes .................................................................................................. 23
Figure 11. AC Common Mode ...................................................................................................... 24
Figure 12. DC Test Modes ............................................................................................................ 25
Figure 13. Digital Signals .............................................................................................................. 26
Figure 14. Analog Signals ............................................................................................................. 28
Figure 15. DAC Output Attenuation Settings ................................................................................ 29
Figure 16. Voltage Reference Circuit ............................................................................................ 31
Figure 17. Power Supply Diagram ................................................................................................ 33
LIST OF TABLES
Table 1. Selections for Operational Mode and DAC Attenuation .................................................... 4
Table 2. Operational Modes.......................................................................................................... 22
Table 3. Output Coding for the CS5373A Modulator and CS5378 Digital Filter Combination ...... 22
DS703F1
3
CS5373A
1.
•
•
•
•
CHARACTERISTICS AND SPECIFICATIONS
Min / Max characteristics and specifications are guaranteed over the
Specified Operating Conditions.
Typical performance characteristics and specifications are measured at nominal supply voltages and T
A
= 25°C.
GND = 0 V. Single-ended voltages with respect to GND, differential voltages with respect to opposite half.
Device is connected as shown in
Figure 8 on page 20
unless otherwise noted.
SPECIFIED OPERATING CONDITIONS
Parameter
Bipolar Power Supplies
Positive Analog
Negative Analog
Positive Digital
Voltage Reference
{VREF+} - {VREF-}
VREF-
Thermal
Ambient Operating Temperature
Industrial (-ISZ)
T
A
-40
25
85
°C
(Note
2, 3)
(Note
4)
VREF
VREF-
-
-
2.500
VA -
-
-
V
V
Symbol
Min
2.45
-2.45
3.20
Nom
2.50
-2.50
3.30
Max
2.55
-2.55
3.40
Unit
V
V
V
±
2%
(Note
1)
±
2%
±
3%
VA+
VA-
VD
Notes: 1. VA- must always be the most-negative input voltage to avoid potential SCR latch-up conditions.
2. By design, a 2.500 V voltage reference input results in the best signal-to-noise performance.
3. Full-scale accuracy is directly proportional to the voltage reference absolute accuracy.
4. VREF inputs must satisfy: VA- < VREF- < VREF+ < VA+.
Modes of Operation
MODE
Selection [2:0]
0
1
2
3
4
5
6
7
000
001
010
0 11
100
101
11 0
111
Selection
Mode Description
DAC Attenuation
ATT[2:0]
000
001
010
0 11
100
101
11 0
111
Attenuation
1/1
1/2
1/4
1/8
1/16
1/32
1/64
reserved
dB
0 dB
-6.02 dB
-12.04 dB
-18.06 dB
-24.08 dB
-30.10 dB
-36.12 dB
reserved
Modulator:
enabled.
DAC:
sleep.
Modulator:
enabled.
DAC:
AC OUT and BUF outputs.
Modulator:
enabled.
DAC:
AC OUT only, BUF high-z.
Modulator:
enabled.
DAC:
AC BUF only, OUT high-z.
Modulator:
enabled.
DAC:
DC common mode output.
Modulator:
enabled.
DAC:
DC differential output.
Modulator:
enabled.
DAC:
AC common mode output.
Modulator:
sleep.
DAC:
sleep.
0
1
2
3
4
5
6
7
Table 1. Selections for Operational Mode and DAC Attenuation
4
DS703F1
CS5373A
TEMPERATURE CONDITIONS
Parameter
Ambient Operating Temperature
Storage Temperature Range
Allowable Junction Temperature
Junction to Ambient Thermal Impedance (4-layer PCB)
Symbol
T
A
T
STR
T
JCT
Θ
JA
Min
-40
-65
-
-
Typ
-
-
-
65
Max
85
150
125
-
Unit
ºC
ºC
ºC
ºC / W
ABSOLUTE MAXIMUM RATINGS
Parameter
DC Power Supplies
Positive Analog
Negative Analog
Digital
(VA+) - (VA-)
(VD) - (VA-)
(Note
5)
(Note
5, 6)
(Note
5)
Symbol
VA+
VA-
VD
VA
DIFF
VD
DIFF
I
PWR
I
IN
I
OUT
PDN
V
INA
V
IND
Min
-0.5
-6.8
-0.5
-
-
-
-
-
-
(VA-) - 0.5
-0.5
Max
6.8
0.5
6.8
6.8
7.6
Parameter
V
V
V
V
V
mA
mA
mA
mW
V
V
Analog Supply Differential
Digital Supply Differential
Input Current, Power Supplies
Input Current, Any Pin Except Supplies
Output Current
Power Dissipation
Analog Input Voltages
Digital Input Voltages
±
50
±
10
±
25
500
(VA+) + 0.5
(VD) + 0.5
WARNING: Operation at or beyond these limits may result in permanent damage to the device.
Normal operation is not guaranteed at these extremes.
Notes: 5. Transient currents up to
±
100 mA will not cause SCR latch-up.
6. Includes continuous over-voltage conditions at the modulator analog input pins.
DS703F1
5
Wireless Connectivity
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